Question: Simplify the following expression: $y = \dfrac{7}{2x} + \dfrac{7}{5x}$
Solution: In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $2x$ and $5x$ $\lcm(2x, 5x) = 10x$ $ y = \dfrac{5}{5} \cdot \dfrac{7}{2x} + \dfrac{2}{2} \cdot \dfrac{7}{5x} $ $y = \dfrac{35}{10x} + \dfrac{14}{10x}$ $y = \dfrac{35 +14}{10x}$ $y = \dfrac{49}{10x}$